1. Field of the Invention
The invention relates to wire book binders and more particularly to the manufacture of binders having alternate wide and narrow loops extending in opposite directions, referred as zigzag wire binders.
2. Description of the Prior Art
A common method of manufacture of zigzag wire binders is to form a continuous strip of wire in looped or zigzag form, which is curved transversely to a partly closed form. The bindery will purchase drums of this preformed material which it places in a book binding machine. This machine will sever lengths of binder from the strip and close the binder by inserting the loops into the perforations along the spine of the book. Another procedure for binding books with zigzag wire binders is for the bindery to purchase already cut lengths of partly closed binders which are singly wrapped to prevent snarling. These are placed individually over the groups of sheets and the loops inserted in the perforations by a hand operated fixture.
Various constructions for inserting the wire loops in the perforations are known. Among them are those disclosed in the following patents and which are not believed to have the advantages of the present invention:
______________________________________ 2,555,290 November May 29, 1951 2,272,339 Goodloe February 10, 1942 3,334,918 Pigna et al August 8, 1967 3,451,081 Liouville June 24, 1969 3,667,076 Aglaghanian et al June 6, 1972 3,854,158 Pigna et al December 17, 1974 3,883,916 Adams et al May 20, 1975 3,889,309 Adams et al June 17, 1975 4,020,516 Gomez May 3, 1977 4,031,585 Adams June 28, 1977 ______________________________________